1) Field of the Invention
The present invention relates to a modified polyoxyalkylene polyamine, a curing agent for epoxy resin comprising said modified polyoxyalkylene polyamine, an epoxy resin composition comprising said curing agent for epoxy resin, and an epoxy resin cured product obtainable by curing said epoxy resin composition.
The modified polyoxyalkylene polyamine is applicable to a curing agent for epoxy resin and a raw material thereof to be utilized in an extremely wide field including application to a coating material, a material for electricity and electronics, a civil engineering and construction material, an adhesive, and a composite material, and is applicable to a chain extender and a raw material thereof of a polyurethane resin.
Furthermore, it can be utilized widely in various field such as a paper reinforcing agent, chemicals for rubber, boiler compounds, a slag inhibitor, a surfactant, an emulsifier, a dye, a pigment, a dyeing assistant, an oil solution for fiber, cosmetics, a crease-proofing agent, a chelating agent, an ore floatation agent, a detergent, a thixotropic agent, a pH adjuster, a pesticide, a herbicide, a stabilizer for agricultural chemicals, feed additives, catalysts, a polymerization accelerator, a polymerization inhibitor, a stabilizer, an ion-exchange resin, a gas absorbent, an antioxidant, a corrosion inhibitor, an antirust, a sterilizer, an antibacterial agent, an antifreeze liquid, a lubrication oil, a lubricant, an intermediate of pharmaceuticals, polyamide, a solvent and photographic chemicals.
2) Related Art
It has widely been known that various chain aliphatic polyamines are used as a curing agent for epoxy resin and a raw material thereof or a chain extender for polyurethane resin and a raw material thereof. Representative examples of these chain aliphatic polyamines include polyethylene polyamines such as diethylenetriamine and triethylenetetramine, each of which has been widely used.
However, these polyethylene polyamines generally have high vapor pressure and strong skin irritativeness. Moreover, an epoxy resin cured product using a curing agent for epoxy resin comprising these polyethylene polyamines as a raw material is inferior in chemical resistance.
Therefore, as a curing agent for epoxy resin, these polyethylene polyamines are scarcely used as it is recently. In most cases, they are used after various modifications of amino groups they have, depending on the intended purpose such as the improvement in safety and hygiene, in workability and in chemical resistance.
Representative methods for a modification of polyethylene polyamines include 1) a modification by Mannich reaction with a phenol compound and an aldehyde compound, 2) a modification by reaction with an epoxy compound, 3) a modification by reaction with a compound having a carboxyl group, 4) a modification by Michael reaction with an acryl compound and 5) combinations of any of 1) to 4).
In general, a molar number of modification of polyethylene polyamine is selected from the range wherein the obtainable modified polyethylene polyamine has at least one active hydrogen atom derived from the amino groups in the polyethylene polyamine before modification.
When the molar number of modification is relatively low, the obtainable modified polyethylene polyamine has a low viscosity. However, the amount of unreacted polyethylene polyamine becomes large, which causes such defects that the obtainable modified polyethylene polyamine may have high toxicity and its skin irritativeness may remain. In addition, a curing agent for epoxy resin using such modified polyethylene polyamine may be inferior in chemical resistance of a cured product.
On the other hand, when the molar number of modification is relatively high, the content of unreacted polyethylene polyamine in the obtainable modified polyethylene polyamine is small. However, the viscosity of the modified polyethylene polyamine becomes high, which brings about the requirement of lowering the viscosity by adding solvents or diluents in order to improve workability.
It is desired not to use solvents in light of environmental problems and it is necessary to limit the amount of diluents added in order to avoid the deterioration of the chemical resistance of a cured product.
Consequently, polyoxyalkylene polyamine has been developed as an alternative to polyethylene polyamine. Since polyoxyalkylene polyamine has relatively low vapor pressure and week skin irritativeness compared to polyethylene polyamine, the purpose such as improving in safety and hygiene and in workability has been accomplished.
However, a curing agent for epoxy resin using polyoxyalkylene polyamine as a raw material is not satisfactory in chemical resistance of a cured product. Therefore, polyoxyalkylene polyamine should also be modified in its amino groups in order to achieve the purpose such as the improvement of chemical resistance.
Representative methods for modification of polyoxyalkylene polyamine include the same methods as the above-mentioned modification methods of polyethylene polyamine.
In general, the molar number of modification of polyoxyalkylene polyamine can be selected from the range wherein the obtainable modified polyoxyalkylene polyamine has at least one active hydrogen atom derived from the amino groups in the polyoxyalkylene polyamine before modification.
When the molar number of modification is relatively low, the obtainable modified polyoxyalkylene polyamine has a low viscosity. However, the amount of unreacted polyoxyalkylene polyamine becomes large, which causes such defects that a curing agent for epoxy resin using the obtainable modified polyoxyalkylene polyamine as a raw material may be inferior in chemical resistance of a cured product.
On the other hand, when the molar number of modification is relatively high, the content of unreacted polyoxyalkylene polyamine in the obtainable modified polyoxyalkylene polyamine is small. However, the viscosity of the modified polyoxyalkylene polyamine becomes high, which brings about the requirement of lowering the viscosity by adding solvents or diluents in order to improve workability.
It is desired not to use solvents in light of environmental problems and it is necessary to limit the amount of diluents added in order to avoid the deterioration of the chemical resistance of a cured product.